Comparison of Electron-Proton and Positron-Proton Elastic Scattering at Four-Momentum Transfers up to 5.0(GeV/c)2

Abstract

Measurements of the ratio ($R$) of positron-proton and electron-proton elastic-scattering cross sections have been made, with the square of the four-momentum transfer ($q^2$) equal to 0.20, 0.69, 0.73, 1.54, 2.44, 3.27, 3.79, and 5.00 ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$. The measurements, after radiative corrections, are consistent with $R=1\mathrm{}$, with standard errors ranging from ±0.016 to ±0.123. The results give limits for the size of the two-photon effects.